CD/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby Tim reads from a typed letter. TIM: Dear Tim and Moby, how do CDs work? From, Chris007. Moby removes a CD from a toaster as if it were a slice of toast. The CD goes limp. TIM: Hey, was that one of mine? Moby hides the CD behind his back. Tim grunts in disapproval. TIM: CD stands for "compact disc". An image shows the recorded, or bottom, side of a CD. TIM: A CD consists of a thin layer of aluminum, sandwiched between a thick layer of plastic and a thin lacquer coating. The CD turns sideways, and labels identify its layers as Tim describes. TIM: The sound is recorded onto the plastic part of the CD as a spiral track of tiny bumps on the surface of the disc. These bumps represent bits, binary digits of 1 or 0. The track starts at the CD's center and winds around the circular disc until it reaches the edge. An image shows the CD's plastic side, which is covered in a spiral of bumps. TIM: It's only about a half a micron wide. That's thinner than a strand of hair. A label shows that one of the spiral lines is half a micron wide. TIM: Believe it or not, this track is over five kilometers long. To play a CD, a drive motor spins the disc between 200 and 500 rotations per minute while a laser scans across the surface. The laser detects the difference in light being reflected by a bump or a flat surface and interprets the surface as a string of 1's and 0's. An animation shows a spinning CD. Its bumps are being read by a laser in a CD player. TIM: The electronics in your CD player convert this data into an audio signal that is sent to your stereo's amplifier and then played through the speakers. An animation shows a stereo system. A simple electronic tune plays. MOBY: Beep. TIM: A computer's CD-ROM is almost exactly the same thing. It's just that the data's in a different format. MOBY: Beep. TIM: DVDs, or digital video discs are similar to CDs, but the bumps are much smaller. Smaller bumps means that they can hold more information. MOBY: Beep. Moby picks up a remote control and turns on a television and DVD player. The TV plays a scene from the DVD "2001: A Space Odyssey." TIM: Your average music CD can store around 650 million bytes of data, while a DVD can hold about 4.7 billion, enough for a whole movie, soundtracks, features, and subtitles in multiple languages. Side-by-side animations show a CD and its capacity compared with a DVD and its larger capacity. MOBY: Beep. Moby shows Tim a music CD with Moby's picture on its sleeve. TIM: You recorded an album? MOBY: Beep beep. Tim looks at Moby's CD, which is entitled "Moby (the robot): My Best Love Songs." TIM: Well, let's hear it. Tim puts the CD into the player. An atonal jumble of electronic sounds is heard. Tim closes his eyes as though he is in pain. TIM: Oh, that's terrible! His eyes open, and his expression softens. TIM: And yet, it makes me want to dance. Category:BrainPOP Transcripts